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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 03 Jan 2010, 16:16 
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Joined: 03 Aug 2008, 20:22
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Location: Denver, Colorado
Mike,

Sounds like a great project,

As far as tubes, another DIY'r and I uploaded some models last year, I just have to find the threads.


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PostPosted: 15 Jan 2010, 18:57 
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Joined: 15 Dec 2009, 20:49
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Hello Roggom,

This is fascinating!

Any idea if the tube stage alone, as presented in your schematic posted on January 1st, could drive a solid state (SS) power amp with an input impedance of say 22K to 47K Ohms without getting bogged down?

Can't wait for your next update.

Best regards,

Obe1


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PostPosted: 16 Jan 2010, 01:57 
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Location: Denver, Colorado
Hi Obe1,

The tube stage is a common cathode, the output impedance is about 2.8k ohms with a gain of about 6 real world. It would be best to use the whole circuit as a line stage amp, as the mosfet buffer will drop the output impedance to 3.2 with a damping factor of 10.

Thanks for the comments, keep a look out for the new version. I am just doing some last minute tweaks.


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PostPosted: 16 Jan 2010, 19:02 
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Thank's Roggom,

I'm anxious to see what you've come up with!

Obe1


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PostPosted: 15 Mar 2010, 00:35 
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Joined: 07 Mar 2010, 23:44
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roggom wrote:
Hi John,
Its been a while,
Your idea can be achieved by eliminating the voltage regulator and using the heater as a source load, but there will have to be some further modification for proper mosfet bias and plate voltage, as the B+ will have to increase.

Pete Millet has done this with his Starving student amp. http://www.pmillett.com/starving.htm


For current time I have a pcb constructed and want to make it as simple and low part count as possible. This way someone with very little electronics background can make a tube amp. I am finishing the tutorial and now going over some casing ideas.

Here is a peek at the prototype pcb. The new version is has less unused space in front and back measures around 50mm x 105mm.

Hi Roggom,
Would you please show the schematic of the "prototype", I like the simple & small !!!
Thanks !


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PostPosted: 15 Mar 2010, 12:23 
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Joined: 28 May 2008, 21:53
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I'll take the blame for this as I have not had time to get Rogers updated project on the site. :( The good news is I actually started pulling together a page yesterday evening so it is next in the queue and will be up in 2 weeks or less. Really, I mean is this time! :angel:

Cheers

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PostPosted: 16 Mar 2010, 22:31 
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Hi Roggom,
Why in your "Prototype Photo", the Mosfet and LM317 are without heat sinks ?
Thanks !


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PostPosted: 19 Mar 2010, 15:02 
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I did the math according to the datasheets and the fets and regulators can dissapate enough heat to air and remain stable. This is of course using a 12~13 volt power supply max.

I have now been running the proto for a few months and have left it on for about a week and no issues.


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PostPosted: 12 Apr 2010, 17:59 
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Sorry for the delay folks and thanks for being patient.

The update to this project is now on the site. See NP-100v12: DIY 12AU7 (ECC82) Tube / IRF510 MOSFET Headphone Amplifier for full details.

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PostPosted: 27 Aug 2010, 08:33 
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Joined: 27 Aug 2010, 07:47
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Hey guys! I'm new here, and new to tubes also... I have wanted to build something arround tubes for a long time now, and I think this amp is my best shot as a first project.

I have some questions though...
- I want to experience tube sound... should I use the original low plate voltage or rise it a bit?
- How do I connect the filaments? 12AU7 has a center tap for the fils, does it go straight to ground (with both ends to 12V) or should I connect them in series leaving 6v each?
- I'm planning on using a 15v tranny for the power supply. After the diodes and 4700u cap, will an LM317 (with caps for ripple rejection as shown in the ic's datasheet) be enough for a good DC or should I use some extra filtering?

Regarding the cans, I'm yet to buy ones...
- I've read reviews on senn's HD205 and they unanimously find them too bassy and dead on the highs... will it get any better with this amp? has anyone tried them?
- Has anyone tried Edifier's H800?
Bear in mind that I live in Argentina (third world... duh) so my options are very limited.

Thanks in advance!
Augusto.


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